This paper reports some results of geoscientific investigations of the shallow subsurface beneath the Nazca geoglyphs in the stone desert in southern Peru. A resistivity and georadar survey was accompanied by soil sam...This paper reports some results of geoscientific investigations of the shallow subsurface beneath the Nazca geoglyphs in the stone desert in southern Peru. A resistivity and georadar survey was accompanied by soil sampling at a test site in the Palpa district. The resulting images of the two geophysical methods indicate similar structures. Georadar enables a fast and continuous data acquisition but is restricted in its depth of penetration. Despite the dry surface conditions, the electrical method yielded good results in the desert area. The resulting resistivity images for both vertical and horizontal slices provide structural information that might be interpreted in terms of lithology and water content. A promising correlation between sulfate content and electrical resistivity at shallow depth was observed that might be helpful to provide insight into the migration of chemical constituents. The approach to combine geophysical, mineralogical and geochemical methods proves to be successful to extend the knowledge on the weathering processes in the desert soil.展开更多
The study region is seismically and tectonically characterized by the angle variations in the subduction of the Nazca plate. The results obtained from earthquakes location between 32° and 36°S latitude and67...The study region is seismically and tectonically characterized by the angle variations in the subduction of the Nazca plate. The results obtained from earthquakes location between 32° and 36°S latitude and67°-71°W longitude are presented in this work. The presence of a wedge of asthenospheric materials and the partial or total eclogitization of the subducted Nazca plate and its relation with isostatic cortex models published was analyzed. In addition, a gravimetric profile obtained from gravity forward modeling is presented at 33.5°S, proposing a new configuration at depths for the main tectonic components： Nazca plate, asthenospheric wedge and South American plate. Also, a new density scheme using recently published velocity models was obtained.展开更多
Calculated Bouguer gravity anomalies from the Andean orogenic belt interpreted as derived from regional gravity data to aid understanding of the lithospheric structure and tectonic evolution of the belt.These anomalie...Calculated Bouguer gravity anomalies from the Andean orogenic belt interpreted as derived from regional gravity data to aid understanding of the lithospheric structure and tectonic evolution of the belt.These anomalies reveal lithospheric structures distributed throughout the belt,including linear and circular structures.NE-trending structures reflect sinistral transpression across the northern part of the belt,and NW-trending structures represent dextral transtension in the southern part.These results are supported by gravity-anomaly patterns that demonstrate mantle flow in a trench-parallel direction both northward and southward away from the stagnation band that is beneath the subducting Nazca slab.This mantle flow has served as an important driving force in the evolution of the Andean orogenic belt.Features of the modified tectonic model of the Andean orogenic belt are consistent with the spatial variation in and interpretation of Bouguer gravity anomalies.展开更多
This investigation searches the possible connections between deep and ultra-deep earthquakes in a subduction zone with unique characteristics known as Nazca-South America subduction. The earthquake events occurred in ...This investigation searches the possible connections between deep and ultra-deep earthquakes in a subduction zone with unique characteristics known as Nazca-South America subduction. The earthquake events occurred in an area under the South Atlantic Magnetic Anomaly. The results pointed out that the cyclicity of earthquakes is independent of external factors and linked to internal unknown changes traced or associated with the lithosphere and upper mantle. The malleable minerals or unbreakable material could be due to a bulge of water between the two Nazca slabs sinking. The periodicity noticed from some events is opposite to the Solar Cycles, which means they enhance during the minima of cycles. Therefore, we concluded that these variations might be linked to internal causes below the crust into the lithosphere.展开更多
The study“Archean cratonic mantle recycled at a mid-ocean ridge”on abyssal peridotites from the Southwest Indian Ridge(SWIR)[1]has received wide attention,which may challenge our Africa continental rift at∼135 Ma a...The study“Archean cratonic mantle recycled at a mid-ocean ridge”on abyssal peridotites from the Southwest Indian Ridge(SWIR)[1]has received wide attention,which may challenge our Africa continental rift at∼135 Ma and the subsequent opening/growth of the South Atlantic Ocean(Fig.1b).That is,the eastward Nazca plate subduction beneath South America and E-mail address:yaoling.niu@foxmail.com(Y.Liu).展开更多
文摘This paper reports some results of geoscientific investigations of the shallow subsurface beneath the Nazca geoglyphs in the stone desert in southern Peru. A resistivity and georadar survey was accompanied by soil sampling at a test site in the Palpa district. The resulting images of the two geophysical methods indicate similar structures. Georadar enables a fast and continuous data acquisition but is restricted in its depth of penetration. Despite the dry surface conditions, the electrical method yielded good results in the desert area. The resulting resistivity images for both vertical and horizontal slices provide structural information that might be interpreted in terms of lithology and water content. A promising correlation between sulfate content and electrical resistivity at shallow depth was observed that might be helpful to provide insight into the migration of chemical constituents. The approach to combine geophysical, mineralogical and geochemical methods proves to be successful to extend the knowledge on the weathering processes in the desert soil.
基金funded by PICTO N°254 Riesgo Sismico and PICT2014-19 1697
文摘The study region is seismically and tectonically characterized by the angle variations in the subduction of the Nazca plate. The results obtained from earthquakes location between 32° and 36°S latitude and67°-71°W longitude are presented in this work. The presence of a wedge of asthenospheric materials and the partial or total eclogitization of the subducted Nazca plate and its relation with isostatic cortex models published was analyzed. In addition, a gravimetric profile obtained from gravity forward modeling is presented at 33.5°S, proposing a new configuration at depths for the main tectonic components： Nazca plate, asthenospheric wedge and South American plate. Also, a new density scheme using recently published velocity models was obtained.
基金jointly funded by the Ministry of Science and Technology of the People’s Republic of China (Grant No. 2019YFA0708601-02)the National Natural Science Foundation of China (Grant Nos. 41404070 and 41374101)the China Geological Survey (Grant Nos. DD20201116, DD20190448, DD20221647, DD20221649 and DD201609-05)
文摘Calculated Bouguer gravity anomalies from the Andean orogenic belt interpreted as derived from regional gravity data to aid understanding of the lithospheric structure and tectonic evolution of the belt.These anomalies reveal lithospheric structures distributed throughout the belt,including linear and circular structures.NE-trending structures reflect sinistral transpression across the northern part of the belt,and NW-trending structures represent dextral transtension in the southern part.These results are supported by gravity-anomaly patterns that demonstrate mantle flow in a trench-parallel direction both northward and southward away from the stagnation band that is beneath the subducting Nazca slab.This mantle flow has served as an important driving force in the evolution of the Andean orogenic belt.Features of the modified tectonic model of the Andean orogenic belt are consistent with the spatial variation in and interpretation of Bouguer gravity anomalies.
文摘This investigation searches the possible connections between deep and ultra-deep earthquakes in a subduction zone with unique characteristics known as Nazca-South America subduction. The earthquake events occurred in an area under the South Atlantic Magnetic Anomaly. The results pointed out that the cyclicity of earthquakes is independent of external factors and linked to internal unknown changes traced or associated with the lithosphere and upper mantle. The malleable minerals or unbreakable material could be due to a bulge of water between the two Nazca slabs sinking. The periodicity noticed from some events is opposite to the Solar Cycles, which means they enhance during the minima of cycles. Therefore, we concluded that these variations might be linked to internal causes below the crust into the lithosphere.
基金supported by the National Natural Science Foundation of China(91958215,91014003,41130314,41630968,and U1606401)Shandong Basic Research Office(WSR2023018)the Ministry of Education 111 Project(B18048)。
文摘The study“Archean cratonic mantle recycled at a mid-ocean ridge”on abyssal peridotites from the Southwest Indian Ridge(SWIR)[1]has received wide attention,which may challenge our Africa continental rift at∼135 Ma and the subsequent opening/growth of the South Atlantic Ocean(Fig.1b).That is,the eastward Nazca plate subduction beneath South America and E-mail address:yaoling.niu@foxmail.com(Y.Liu).
